I got a pack of 1000 metallic beads from Amazon for about £4.50. I like to use 550 paracord from the bushcraft store but I was struggling to get the colours from them so ended up buying cheaper stuff. It's not as nice to work with but was ok.

I found a very clear video on youtube (skip to end of post to see it) to follow.

Different colour paracords make different trees and you can even splice the branch cord and make them different colours on the same tree if you like. I tried one with a spliced trunk and spliced branch colours but in the end thought they looked too 'messy' and sometimes sticking to classic is the best thing.

The trunk colour needs about 80cm of paracord to be generous. I got it down to about 60cm once I got confident and had much less wastage.

The branches, depending on their size, need about 130cm.

The start of anything is always the hardest but it's simply a cobra knot start. The video shows it well.